1. Field of the Invention
This invention relates to the field of acid-catalyzed organic reactions and particularly to methods of conducting acid-catalyzed reactions of organic compounds which reactions are promoted by strong acids. The invention also relates to novel acidic compositions useful in such reactions.
2. Description of the Art
Both urea and sulfuric acid are well known and are widely used in numerous industries for a variety of purposes, including their use in fertilizers, soil adjuvants, chemical treating agents, chemical precursors, and reactants. The ability of sulfuric acid to catalyze a variety of organic reactions is also known. Urea and sulfuric acid are sometimes useful in combination, particularly in the agricultural industry when simultaneous addition of urea and sulfur to the soil is desired.
It is also known that urea and sulfuric acid will combine to form adducts including the monourea-sulfuric acid adduct and the diurea-sulfuric acid adduct. For instance, D. F. du Toit, Verslag Akad. Wetenschappen, 22, 573-4 (abstracted in Chemical Abstracts, 8, 2346, 1914) disclosed that urea forms certain compounds with oxalic, acetic hydrochloric, nitric and sulfuric acids. L. H. Dalman, "Ternary Systems of Urea and Acid. I. Urea, Nitric Acid and Water. II. Urea, Sulfuric Acid and Water. III. Urea, Oxalic Acid and Water"; JACS, 56, 549-53 (1934), disclosed the phase relationships between the solid phase and saturated solutions containing urea and sulfuric acid at 10.degree. C. and 25.degree. C. The Sulfur Institute, Sulfur Institute Bulletin No. 10 (1964), "Adding Plant Nutrient Sulfur to Fertilizer", disclosed that urea reacts with sulfuric acid to form two complexes of "urea sulfate" which are useful fertilizers. Methods of manufacturing certain combinations of urea and sulfuric acid are disclosed by Verdegaal et al. in U.S. Pat. No. 4,310,343 and by Jones in U.S. Pat. No. 4,116,664.
A wide variety of organic conversions are catalyzed by the proton-donating ability of strong acids. Such reactions have been extensively investigated and have been widely discussed in the literature. For instance, the Kirk-Othmer Encyclopedia of Chemical Technology, Third Edition, John Wiley and Sons, N.Y., 1980, discusses a variety of organic reactions that are catalyzed by strong acids including mineral acids, transition metal halides such as Friedel-Crafts catalysts, conjugate Friedel-Crafts catalysts, and others. Kirk-Othmer defines acid-catalyzed reactions as those in which a proton is transferred from the catalyst to the reactant which is thereby converted to an unstable state which immediately leads to the reaction under consideration. (Volume 5, page 33). While the proton donation mechanism of acid-catalyzed reactions referred to in Kirk-Othmer may or may not account for the reactions that take place in all acid-catalyzed reactions, it is known that strong acids promote numerous reactions including oxidative addition, reductive addition, esterification, transesterification, hydrogenation, isomerization (including racemization of optical isomers), hydrolysis and alcoholisis, alkylation, olefin polymerization, Friedel-Crafts reactions, demetalization of organics, and nitration reactions, among others. Strong acids known to be capable of promoting such acid-catalyzed organic reactions include sulfuric acid, nitric acid, hydrochloric acid, transition metal halides including the so-called Friedel-Crafts catalysts, for example, the halides of aluminum, gallium, boron, titanium, vanadium, tin and others, and conjugate Friedel-Crafts catalysts also known as Bronsted-Lewis superacid mixtures (Kirk-Othmer, V. 11, 295) such as mineral acid adducts of transition metal halides.
All of the known strong acid catalysts and the methods involving their use for the promotion of acid-catalyzed organic reactions suffer from one or more disadvantages. For instance, the strong mineral acids promote side reactions which form undesired by-products, destroy the organic feed material or product, and/or consume or deactivate the catalyst. Sulfuric acid is a strong sulfating, sulfonating, oxidizing, and dehydrating agent, and by virtue of those activities, it is consumed in most organic reactions by side reactions involving these mechanisms. Furthermore, the sulfonating and oxidizing activities of sulfuric acid results in the sulfonation and oxidation of organic feedstocks and/or products. Similar deficiencies exist with the other strong mineral acids such as hydrochloric and nitric acids. Hydrochloric acid chlorinates the reactants and thereby consumes the feed to produce unwanted chlorinated by-products.
Nitric acid oxidizes and/or nitrates organic compounds. Hydrofluoric acid fluorinates organic reactants and products. The transition metal halides, including the Friedel-Crafts catalysts, are difficult to handle in that they must be isolated from water and reducing agents. Such catalysts also halogenate organic feedstocks and products.
Accordingly, a need exists for improved methods of conducting acid-catalyzed organic reactions and for improved acid catalysts for use in such reactions which will promote the desired acid-catalyzed organic reaction yet reduce or eliminate the side reactions normally associated with acid-catalyzed organic reactions.
It is therefore a principal object of this invention to provide novel methods for the acid-catalyzed conversion of organic compounds.
Another object is the provision of novel methods for conducting acid-catalyzed reactions of organic compounds in the presence of sulfuric acid.
Another object of this invention is the provision of novel acid catalysts comprising sulfuric acid which are effective for conducting acid-catalyzed organic reactions.
Another object of this invention is the provision of novel compositions which are useful for conducting acid-catalyzed organic reactions.
Another object of this invention is the provision of novel catalysts comprising sulfuric acid which have improved activity in the presence of lipophilic materials.
Yet another objective of this invention is the provision of novel methods for catalyzing organic reactions with sulfuric acid.
Another object is the provision of novel methods for the oxidative addition of organic compounds.
Yet another object is the provision of novel methods for the reductive addition of organic compounds.
Another object is the provision of novel sulfuric acid-containing compositions useful for conducting organic reactions.
Another object is the provision of novel methods for the esterification and transesterification of organic compounds.
Yet another object of this invention is the provision of novel methods for hydrogenating organic compounds containing olefinic unsaturation.
Another object is the provision of novel methods for isomerizing organic compounds.
Yet another object is the provision of novel methods for the hydrolysis, alcoholisis, thiolosis, and amination of organic compounds.
Another object is the provision of novel methods for the alkylation of organic compounds.
Yet another object is the provision of novel methods for polymerizing olefinic compounds.
Yet another object is the provision of novel conjugate Friedel-Crafts catalysts.
Another object is the provision of novel Friedel-Crafts catalyzed organic reactions.
Yet another object of this invention is the provision of novel methods for demetalizing organic compounds.
Another object is the provision of novel methods for nitrating organic compounds.
Other objects, aspects and advantages of this invention will be apparent to one skilled in the art in view of the following disclosure and the appended claims.